Apparatus for applying pressure to an advancing web of rigid material

ABSTRACT

A device for exerting an adjustable pressure against one side of continuously moving web of a rigid strip material having the other side thereof contacted by a surface treatment apparatus, including one or more blocks connected to a source of pressurized gaseous medium and having a plane surface in proximately spaced relationship with the first mentioned surface of the web, the surface having gas passageways therein so as to follow the formation of a gas cushion between the web surface and the block which prevents direct contact therebetween while concurrently imparting pressure to the surface of the web in the direction of the surface treatment apparatus.

11] 3,72%,045 51 Apr. 3, 1973 s41 APPARATUS Fo'R APPLYING PRESSURE TO ANADVANCING WEB or morn MATERHAL [75] Inventor: Jacques Max Auvelais,Belgium [73] Assignee: Ateliers Heuze Malevez et Simon Reunis SocieteAnonyrne, Auvelais, Belgium [22] Filed: Mar. 9, 1971 21 Appl, No.:122,327 Foreign Application Priority Data Charles Y Dryon Mar. 10, 1970Belgium 122,327

[52] 11.8. C1. 3.29/90, 51/110, 51/283, 65/61, 83/402 [51] Int. Cl.13241) 39/00 [58] Field of Search ..29/90; 65/256, 61, 254; 51/283, 110,112; 83/402 [56] References Cited UNITED STATES PATENTS 3,176,441 4/1965Walters ..5l/283 Primary ExaminerLeonidas Vlachos AttorneyWaters, Roditi& Schwartz [57] ABSTRACT A device for exerting an adjustable pressureagainst one side of continuously moving web of a rigid strip materialhaving the other side thereof contacted by a surface treatmentapparatus, including one or more blocks connected to a source ofpressurized gaseous medium and having a plane surface in proximatelyspaced relationship with the first mentioned surface of the web, thesurface having gas passageways thereinso as to follow the formation of agas cushion between the web surface and the block which prevents directcontact therebetween while concurrently imparting pressure to thesurface of the web in the direction of the surface treatment apparatus.

8 Claims, 4 Drawing Figures PATENTEDAPR 3 I973 SHEET 2 OF 3 Fig.2.

APPARATUS FOR APPLYING PRESSURE TO AN ADVANCING WEB OF RIGID MATERIALThis invention relates to devices for exerting an adjustable pressure ona given portion of one side of rigid strip material which is beingcarried past continuously. The other side of the strip rests against anyother suitable apparatus, which may optionally perform a treatment onthe other side.

Devices of this nature are employed in glass production lines employingthe so-called float glass" process. In these it may be profitable toimpart a'finish to the lower side of the strip or web.

At present these devices apply the lower side of the glass web againstthe felts of a polishing apparatus Also a plane surface made up from aseries of parallel rollers arranged on a frame permits freeing of theglass web. In use the frame which can be moved vertically, depresses therollers onto the upper side of the web and applies the lower sideagainst the felts of the polishing plates. The pressure exerted on thefelts depends on the weight of the frame and of the rollers.Counterweights are generally incorporated which enable the exertedpressure to be varied. The rollers are journalled on bearings and havetheir axes perpendicular to the direction of travel of the web.

These devices suffer from the following shortcomings:

i. the pressure applied by the rollers to the glass web operates throughthe contacting surfaces of the rollers, and this area is necessarilysmall. The pressure is designed to be transmitted as uniformly aspossible, so that the polishing work is spread over the glass surface;

ii. the rollers rest on glass and they are caused to rotate by theforward moment of the web;

iii. sudden local variations in thickness in the web cause the completeframe to rise, resulting in a substantial local overpressure;

iv. if a narrow web for a given frame is used, the rollers projectbeyond the web which causes premature deterioration of their rubberfacing.

The present invention provides a device comprising one or more blockswhose weight is controllable and whereof the face facing towards the webis furnished with elements allowing the passage of a gas under pressure,in such manner as to form a gaseous cushion preventing direct contactbetween the web and the block or set of blocks.

The weight of blocks can be adjusted by the addition or removal of unitsofa given weight.

A plurality of small orifices or discs of porous material can beattached to the plane lower surface of each block to allow gas toemanate from each block. Conveniently a flexible hose is used to feedgas under pressure to each block.

The block or set of blocks is carried on a frame capable of being raisedin order to free the web. Optionally each block of the set of blocks maybe raised separately. In this way the spread of the gaseous cushion caneasily be matched to the width of the web.

The presence of a gaseous cushion between the blocks and'the web canreduce frictional forces opposing the displacement of the web.

The block surfaces facing towards the web can be plane and parallel tothat of the web so that the pressure corresponding to the weight of theblocks exerted onto the web is distributed uniformly.

Because the blocks are independent, superfluous blocks can easily bewithdrawn when the web width is changed. Any local variation in thethickness of the web should not produce a substantial localoverpressure, for the blocks being used are arranged to match thethickness of the web.

The pressure of the gas is adjusted depending on the weight of theblocks and on the cushion thickness required. To polish the lower sideof the web, the pressure through the gaseous cushion exerted by the theblocks against the upper side of the web should be approximately 20kgsldm The present invention is described by way of a nonlimitingexample with reference to the accompanying drawings.

FIG. 1 is a section of the device taken along the line I--I of FIG. 2 ina plane perpendicular to the direction of travel of the web;

FIG. 2 is a section taken along the line II-II of FIG.

FIGS. 3 and 4 are sections on an enlarged scale of two kinds of block.

The plant comprises a polishing appliance 1 in which the felts 2 are incontact with the side 3 of the glass web 4.

The surface 3 is applied against the felts under pressure through adevice which, according to the invention, comprises adjacent blocks 5held within a frame 6. This frame 6 can be raised by means of jacks 7,designed to withdraw, if need be, the set of blocks 5 from the side 8 ofthe web.

On top of each block 5 is fastened by means of screws 9 a plate 10, thedimensions of which are a little smaller than the lower part 5' of theblock, but greater than those of the upper part 5". Hence recesses 11are formed within the blocks, in which the elements of the frame 6 canfit. Each block 5 can move up and down freely in a vertical direction asdefined by the limits of the recesses 11. Each block contains adistribution system from gas under pressure entering through a pipe 12screwed onto the block and connected to the duct 13 by means of aflexible hose 14. The pipe 12 fits onto a passage 15 passing through theblock. The passage 15 opens into a cavity 16 defined by the block 5' anda sole" 17 which is secured to the former by means of the screws 18.Either nozzles 19 (FIG. 3) with a lower orifice of small diameter, orporous discs 20 (FIG. 4) are arranged in this sole plate. The gas underpressure maintains a gas cushion between the plane lower surface of thesole plate 17 and the upper side 8 of the web 4. The thickness of thegas cushion should be as thin as possible without allowing directcontact between the set of blocks 5 and the side 8 of the web.

Each block can withdrawn separately from the web 4 by causing anabutment 21 secured to the pipe 12 to be lifted by the cross-member 22of the frame. Thus the number of blocks in use can be adjusted for thewidth of the web.

The weight of each block 5 and the pressure on the web through the gascushion is adjusted by adding or removing from block 5 weights 23 equalin size to the plate 9.

The gas, for example air, which enters through the duct 13 will firsthave passed through a pressure-control device (not illustrated). Thepressure level is determined by the required air cushion thickness, aswell as the weight of the blocks. The gas air feed to unused blocks canbe shut off by cocks 24.

The invention is evidently not limited to the embodiments which havebeen described and illustrated in the example, and its scope would notbe exceeded by making modifications in these.

I claim 1. Device for exerting an adjustable pressure against onesurface of a web continuously conveyed therepast and the other surfaceof which is being contacted by a surface treatment apparatus, saiddevice comprising; at least one block having a plane surface facingtoward said first-mentioned surface of the web; means for adjusting theweight of said block; means for supplying a flow of a pressurizedgaseous medium through said block toward said plane surface; meanspositioned in said block allowing passage of said gaseous medium throughsaid plane surface so as to form a gas cushion intermediate the planesurface and said web to thereby prevent contact between said block andsaid web while concurrently imparting pressure on said web in thedirection of the surface treatment apparatus.

2. Device as claimed in claim 1, said means allowing passage of saidgaseous medium through said plane surface comprising at least one smalldiameter orifice communicating said gaseous medium supplying means withsaid plane surface.

3. Device as claimed in claim 1, said means allowing passage of saidgaseous medium through said plane surface comprising gas-pervious porousdiscs positioned in said block.

4. Device as claimed in claim 1, comprising removable weights adapted tobe mounted on said block for adjusting the weight thereof.

5. Device claimed in claim 1, comprising frame means supporting saidblock; and means for raising said frame means for lifting said blockaway from said web.

6. Device as claimed in claim 1, said gaseous medium supplying meanscomprising a flexible hose connected to said block.

7. Device as claimed in claim 1, comprising a plurality of said blocksextending laterally across the width of said web for imparting pressurethereagainst.

8. Device as claimed in claim 7, comprising frame means supporting eachof said blocks, said blocks being individually removable from said framemeans for correlating the quantity of blocks with the width of said web.

1. Device for exerting an adjustable pressure against one surface of aweb continuously conveyed therepast and the other surface of which isbeing contacted by a surface treatment apparatus, said devicecomprising; at least one block having a plane surface facing toward saidfirst-mentioned surface of the web; means for adjusting the weight ofsaid block; means for supplying a flow of a pressurized gaseous mediumthrough said block toward said plane surface; means positioned in saidblock allowing passage of said gaseous medium through said plane surfaceso as to form a gas cushion intermediate the plane surface and said webto thereby prevent contact between said block and said web whileconcurrently imparting pressure on said web in the direction of thesurface treatment apparatus.
 2. Device as claimed in claim 1, said meansallowing passage of said gaseous medium through said plane surfacecomprising at least one small diameter orifice communicating saidgaseous medium supplying means with said plane surface.
 3. Device asclaimed in claim 1, said means allowing passage of said gaseous mediumthrough said plane surface comprising gas-pervious porous discspositioned in said block.
 4. Device as claimed in claim 1, comprisingremovable weights adapted to be mounted on said block for adjusting theweight thereof.
 5. Device claimed in claim 1, comprising frame meanssupporting said block; and means for raising said frame means forlifting said block away from said web.
 6. Device as claimed in claim 1,said gaseous medium supplying means comprising a flexible hose connectedto said block.
 7. Device as claimed in claim 1, comprising a pluralityof said blocks extending laterally across the width of said web forimparting pressure thereagainst.
 8. Device as claimed in claim 7,comprising frame means supporting each of said blocks, said blocks beingindividually removable from said frame means for correlating thequantity of blocks with the width of said web.